SA-15 Enclosure Etc.

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Good day all = ) New to the forum & this is my first post. This is also my first Sundown sub so definitely want to get this right. Despite getting a lot of help from my local dealer & another experienced party, was hoping for some feedback concerning the specs I intend on going with. Always like hearing different perspectives on matters such as these.

Firstly, will be playing this with 1200w @ 1 ohm. Coming up with 4.54 ft^3 gross, 3.2 ft^3 net. 2 x 15" x 2" ports (60 sq. inches), 26" long tuned to around 34 Hz. Enclosure itself will be 41" W x 16.5" D x 14.75" H. Sub & ports on same face. Sub to the middle, a port on either side. Firing upward in a wagon.

As a personal preference, I rather a peak at around 36-38 Hz. Not a big fan of 40+ so rather that be on the downward slope. Really like my low end & would have probably tuned to 32 Hz but was advised against doing so. I'm aware that despite the sub being rated @ 750w rms, it can take more due to being under-rated. Putting 1200w on it is still over the rated power & so going with a smaller net of 3.2 ft^3 was the more safe path to take. Would a larger net volume with a lower tuning have been very risky or possibly affect the life of the woofer significantly?

Before pulling the trigger on the SA, my intention was to go with two E-Series v3 15". In your experience, what would have been the differences between the two options? Very happy with my SA decision but very curious as to how they would compare. Tempted to test this for science purposes.

Any feedback/knowledge/opinions will be greatly appreciated. Thanks! = )

You box net volume and tuning should be fine, though your port length is short if you want to tune to 34 Hz. To tune to 34 Hz I calculate your ports need to be 35" long each. You will have to adjust your external box dimensions to keep the net volume the same.

As far as an E-15 vs a SA-15. Here is a comparison of the two in the same size box. SA-15 is the green line and E-15 is the yellow:
Their frequency response is pretty similar. Note that this graph is raw output, cabin gain is not included and will boost the low end significantly. Based on the power you are running I think the SA-15 was the right choice.

Edited July 19 by Triticum Agricolam

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Thanks for the reply bro. That's a significant difference in porth length O_o Will have to add approximately 0.43 ft^3 to cater for the addition. Also, I will have to wrap the port in a "U" for it to fit probably. There was a distance of 11.5" between the port openings inside the box.

I used a random port calculator online. One of the very few that I found which asks for the number of slot ports. This leads me to the question, how do I know which calculators will give me an accurate port length? The calculator gave me a similar length to one of the persons who helped with the specs. I'm guessing he used a calculator of his own as well. If it's not too much trouble, did you use one as well? & if yes, which was it? Wouldn't mind fiddling around with it to see for myself.

With regards to the SA vs the E, did you mean the SA was the right choice 1 sub vs 1 sub? Or the 2 E-15s vs 1 SA-15?

Thanks for the reply bro. That's a significant difference in porth length O_o Will have to add approximately 0.43 ft^3 to cater for the addition. Also, I will have to wrap the port in a "U" for it to fit probably. There was a distance of 11.5" between the port openings inside the box.

I used a random port calculator online. One of the very few that I found which asks for the number of slot ports. This leads me to the question, how do I know which calculators will give me an accurate port length? The calculator gave me a similar length to one of the persons who helped with the specs. I'm guessing he used a calculator of his own as well. If it's not too much trouble, did you use one as well? & if yes, which was it? Wouldn't mind fiddling around with it to see for myself.

With regards to the SA vs the E, did you mean the SA was the right choice 1 sub vs 1 sub? Or the 2 E-15s vs 1 SA-15?

Thanks again = )

So the proper way to calculate port length with two ports is to plug the numbers in for one port and divide your box volume in half. So for a 3.2 cu ft net volume box with two 2" x 15" ports you would calculated it like a 1.6 cu ft box with a single 2" x 15" port. In your case, if you are tight on space my suggestion would be to use one port if you can. It takes up less space due to having less internal panels. Also 60 sq in of port area is a bit more than you need. There is nothing wrong with having more than you need and with multiple ports its better to be on the high side for port area since multiples port are less efficient, but if you switched to a single port, 45 sq in (3" x 15") would work just fine.

With regards to the SA-15 vs E-15, I didn't see that you were looking at TWO E-15s vs ONE SA-15. Either of those would work well in terms of power handling, but the two E-15s would have needed a box twice as big.

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So you were definitely right, we double checked the ports & I'm not quite certain what happened before but I'm getting similar figures in terms of the lengths now. With the longer ports it might really be better to go with the single port & it would also cut down on some material/volume. Would the single port @ 60 sq. in. be okay?

Yup @ twice the box size, was fitting pretty snug but it would have fit.

So, the plot thickens...

Was really hoping to move a bit more air, hence the two 15s & coming from a few other multi-woofer setups. The option to go with an Obsidian 18 has presented itself. The question is, do I got with the OA- 18 or stick to the SA-15. Space, although it'd be nice to keep some, isn't a priority.

Pros of going OA-18: Ever so slightly better/smoother on low end? Moving more air. More output in right enclosure. Unique factor of running an 18". Maximizing the limited power I have.

Cons of going OA-18: Extra cost. Larger enclosure. Rated less power than the SA series. Read that it's not as good with thermal handling. Had my heart set on Sundown Audio for years.

It's a pretty tough decision. Back & forth between the two constantly. Has anyone had experience with both & can point out any factors I may have missed? Was told that they are basically the same speakers with very minor differences. Was even considering trying to order/ship the SA-18 due to it being discontinued & not being available where I am from.

Thoughts?

Edited July 20 by image91

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Made the decision to get the Obsidian 18. Collected it yesterday. Bitter-sweet. Was hard sending back the SA. Appreciate all the help with the SA specs Triticum Agricolam. Now I need to plan something out for the 18.

Should I move this to another forum? Technically it's no longer under Sundown unfortunately. The topic also no longer applies.